What Causes Swelling In The Clitoris?

my boyfriend told me two days ago that i felt unusually swollen on the inside. it has gotten worse now, and i am scared. i ended my last period less than a week ago, maybe 5 days, but i tried those rephresh tampons for the first time. i also tried one of those home detection kits for infections lasst night and it was normal. what do i do now, and is this something i can pass on to my boyfriend, or him to me? he has been my only partner for quite some time.